Although the reality star, 31, has yet to finalize her divorce from NBA player Kris Humphries, she and the rapper, 34, "are talking marriage," says the source. (Over the weekend, Kardashian jetted back from Washington, D.C., where she was a guest at the White House Correspondents' Dinner on Saturday, to be by West's side for a Sunday performance of Broadway's "Wicked.")

A sure sign of Kardashian's commitment? The workaholic star will join the Grammy winner on his summer tour with Jay-Z. "She wants to be with him as much as possible," the source explains. "They really know and love each other."